It is very interesting how people spell the name Jan Gerritze Bantjes. My great grandfathers name is Jan Gerritze Bantjes. Some people spell his name Gerritse. Yet I have noticed that in the family line some were baptised Gerritse. So the Name Jan Gerritse is correct for some people. And Jan Gerritze for others. I think the Z in the Name is correct as it would come from Nederland. In SA somehow it changed for some to an S.
I do think it's important to get the spelling right. I have a bible that belonged to Jan Gerritze Bantjes. He wrote his own name with a Z as Gerritze. He received this Bible from John G Lake the famous faith healer. I think it is important to add names and dates from proper source documents.